1. Field of the Invention
The present invention relates to a printed circuit board used for various types of electric equipment and electronic equipment.
2. Description of the Background Art
In recent years, electric equipment, electronic equipment and the like (hereinafter abbreviated as electronic equipment and the like) have progressed in digitization while being sophisticated. With the digitization and sophistication, frequencies of digital signals handled in the electronic equipment and the like have become higher.
When the digital signal is handled in the electronic equipment and the like, high frequency noise is likely to be produced due to the harmonic. Thus, the electronic equipment and the like malfunction in some cases. Therefore, a printed circuit board including a low-pass filter has been developed to prevent generation of the high-frequency noise (see JP 2004-254257 A, for example).
In the printed circuit board with the built-in low-pass filter described in JP 2004-254257 A, the low-pass filter is composed of a stripline, a ground capacitor electrode and a ground electrode. This low-pass filter attenuates the harmonic.
In the above-described printed circuit board with the built-in low-pass filter, however, the stripline, the ground capacitor electrode and the ground electrode are formed in different layers. That is, in the configuration of JP 2004-254257 A, it is necessary to provide a number of layers on which the stripline, the ground capacitor electrode and the ground electrode are formed, thereby making it difficult to reduce the printed circuit board in thickness.